JP5148926B2 - Gas shut-off device - Google Patents

Description

  The present invention relates to a gas shut-off device, such as an electronic gas meter, for monitoring a gas flow rate in a gas line connecting a gas supply source and a gas appliance and shutting off the gas when the gas is abnormally used. The present invention relates to a gas cutoff device having a cutoff function.

  Conventionally, an electronic gas meter periodically samples the flow rate of a gas flowing through a gas supply pipe by a flow sensor, and can instantaneously measure the current flow rate of the gas. However, for a stable flow of gas, an accurate flow rate can be captured instantaneously. However, even in a situation where the flow is disturbed by an external influence such as GHP (gas heat pump), the flow rate is kept as it is. Since it catches, it will also lack accuracy.

On the other hand, in addition to the function of measuring the gas flow rate in the gas meter, for example, as disclosed in JP 2001-330493 A (Patent Document 1), JP 2001-330244 A (Patent Document 2), There is a security function called a use time blocking function. This usage time cutoff function sets a limit on the time that can be used for the flow rate being used, and if this limit time (allowable usage time) is exceeded, the gas supply is stopped (shut off). It is a function.
JP 2001-330493 A JP 2001-330244 A

  As described above, the gas meter has a problem in the accuracy of the flow rate measurement in the situation where the gas flow is disturbed. However, the flow rate substantially changes when the usage time cutoff function is also affected by the flow rate fluctuation. It is recognized that the flow rate has changed despite the absence. In this case, there is a possibility that the time limit is restarted at the target flow rate (measured value) after the flow rate change. That is, in spite of a dangerous state, since gas supply is continued, it becomes an unsafe side.

  As a countermeasure in such a case, rather than determining whether or not the time limit control is necessary based on a single flow rate measurement result, the measurement results of a plurality of times are averaged, and whether or not the time limit control is necessary is determined based on the average value. The determination method is general. However, there is a merit that the influence of the flow rate fluctuation becomes less affected as the number of measurement values to be averaged, that is, the average number (average parameter) is increased. There is a demerit that the response to an actual flow rate change becomes slow, particularly in a high flow rate range.

  It is an object of the present invention to ensure the safety performance of the usage time cutoff function even in a situation where the flow rate of gas is varied, and to ensure the determination speed corresponding to the actual flow rate change in the high flow rate region.

The gas shut-off device according to claim 1 measures an instantaneous gas flow rate at a predetermined sampling period, averages the sampling number from a plurality of sampled measurement values as an average number, obtains an average flow rate, and a flow rate range of the average flow rate Is a gas shut-off device that shuts off the gas flow path when it is determined that the gas use state is abnormal based on the allowable use time corresponding to the above, and is activated at a predetermined timing and executed in parallel with the main process. Means realized by interrupt processing, a flow rate change detecting means for detecting a change in gas flow rate, and an average number of said averaging according to the instantaneous flow rate of gas when the flow rate change detecting means detects the flow rate change the average number determining means for determining the allowable use measures time with the use time timer unit, as the average number of said average number determining means for determining, in the case where the low flow high flow A number not to be erroneous determination under flow variation in s, N1 <the first predetermined value N1, the relationship of N2 and the second predetermined value N2 is predetermined, the flow rate variation by the flow change detection unit continues to monitor, there is the underlying flow rate range corresponding flow rate of the allowable use time, and continues to be the absence of flow rate change, when the remaining time of the use time timer becomes zero, blocking determination When the flow rate changes, the average number determining means determines that the average number is the first predetermined value N1 if the instantaneous flow rate is greater than a prescribed flow rate. and to determine the average number of the second predetermined value N2 if not greater than the time of flow rate prescribed rate instantaneous, calculates an average flow rate of the instantaneous flow rate by the average number of which is the determined, the use time from the average flow Controlling the remaining time of the timer part To.

  Here, for example, when considering an actual combustor that uses gas, a combustor in a low flow rate region such as a gas table or a stove is likely to be used at a stable flow rate for a long time. Since the flow rate is more susceptible, it is necessary to average with a larger number of samplings. On the other hand, the hot water heater is used at a high flow rate for a short period of time and requires a quicker reaction because the flow rate changes rapidly. In this case, since the influence of the flow rate fluctuation is very small, sufficient performance can be obtained by averaging a small number of samplings. In this way, by switching the average number (the parameter of averaging) according to the flow rate used, it becomes possible to withstand flow rate fluctuations and have a quick reaction determination.

  According to the gas shut-off device of claim 1, since the average flow rate is obtained with a large average number when the flow rate is low, the influence of the flow rate fluctuation can be reduced, and when the flow rate is high, the average flow rate is obtained with a small average number so As a result, it is possible to ensure the safety performance of the usage time cutoff function and to ensure the determination speed corresponding to the actual flow rate change in the high flow rate region.

In addition, since either the first predetermined value or the second predetermined value is selected as the average number corresponding to the instantaneous flow rate, the processing is simplified.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram of an electronic gas meter as a gas cutoff device according to an embodiment of the present invention, and FIG. 2 is a principal block diagram of the gas meter. As shown in FIG. 2, the gas meter 100 includes a microcomputer (hereinafter referred to as a microcomputer) 10, a flow rate detection unit 20, and a blocking unit 30. The microcomputer 10 includes a CPU 10a that performs various processes according to a processing program, a ROM 10b that stores a program for processes performed by the CPU 10a, a work area (a data storage area that stores various data, etc.) that is used in various processes in the CPU 10a. ), A timer 10d for measuring the gas usage time, and the like, and these elements are connected by a bus line.

  The flow rate detection unit 20 includes a flow rate sensor such as an ultrasonic sensor that can detect an instantaneous flow rate of gas flowing through a gas flow path (not shown). Note that the ultrasonic sensor detects the instantaneous flow rate from the signal propagation time of the ultrasonic signal propagating in the gas flow path, as in Patent Documents 1 and 2. The shut-off unit 30 includes a drive circuit that drives a shut-off valve installed in the gas supply path.

  1 includes a control unit 1, an ultrasonic measurement unit 2, a flow rate monitoring unit 3, an average number determination unit 4, an average value calculation unit 5, a data unit 6, a cutoff time determination unit 7, a usage time timer unit 8, It consists of a blockage determination unit 9. The flow rate monitoring unit 3 is a “flow rate change detecting unit” that detects a change in gas flow rate, and detects a change in flow rate by comparing, for example, a current value and a previous value of an instantaneous flow rate value. The average number determination unit 4 is an “average number determination unit” that determines the average number of averaging. Each functional block includes a function obtained by the CPU 10a of the microcomputer 10 executing a control program, a flow rate detection unit 20, a ROM 10b, an AM 10c, a timer 10d, and the like.

  The control unit 1 instructs the ultrasonic measurement unit 2 to perform measurement. The flow rate monitoring unit 3 monitors the flow rate and notifies the control unit 1 when a flow rate change is detected. The average number determination unit 4 determines the average number n based on the instantaneous flow rate measurement value from the flow rate monitoring unit 3 according to an instruction from the control unit 1 when a flow rate change is detected. The average value calculation unit 5 calculates the average value (average flow rate) of the flow rate measurement values with the average number n determined by the average number determination unit 4, and stores the average value data in the data unit 6.

  The cutoff time determination unit 7, the usage time timer unit 8, and the cutoff determination unit 9 realize the “usage time cutoff function” similar to the conventional one. In other words, in the usage time cutoff function, the cutoff time (allowable usage time) is determined corresponding to each flow rate range obtained by dividing the gas flow rate range corresponding to the gas appliance to be used. The determination unit 7 determines the cutoff time of the corresponding flow rate region from the average flow rate of the data unit 6, and transmits the determined cutoff time to the usage time timer unit 8. Then, the usage time timer unit 8 sets a cutoff time and starts counting down.

Continue the above processing is continued monitoring of the flow rate change by the flow monitoring unit 3, if there is flow rate change, remaining time of the use time timer unit 8 based on the above process is controlled. When the state in which the flow rate does not change continues and the remaining time of the usage time timer unit 8 becomes zero (when time is up), the cutoff determination unit 9 notifies the control unit 2 that the cutoff should be performed. Thereby, the control part 1 interrupts | blocks a gas supply path by the interruption | blocking part 30. FIG.

  FIG. 3 is a main part flowchart in the embodiment. This flowchart shows an interrupt process executed in parallel with the main process in the CPU 10a of the gas meter 100, and the operation will be described with reference to FIG. In the main process, the use time blocking function process and other various processes are performed.

  The process of FIG. 3 is started at a predetermined timing, and in step S1, the presence or absence of a flow rate change is determined based on the measurement value of the ultrasonic measurement unit 2. If there is no flow rate change, the process returns to the original routine and there is a flow rate change. For example, the process after step S2 is performed. In step S2, flow rate measurement is performed by the ultrasonic measurement unit 2 to obtain a flow rate measurement value (instantaneous flow rate) Q, and in step S3, it is determined whether the flow rate measurement value Q is greater than a specified flow rate. If the flow rate measurement value Q is larger than the specified flow rate, it is determined that the flow rate is high, and the average number n is set to N1 (first predetermined value) in step S4, and the process proceeds to step S6. If the flow rate measurement value Q is not larger than the specified flow rate, it is determined that the flow rate is low, and the average number n is set to N2 (second predetermined value) in step S5, and the process proceeds to step S6. Here, the average numbers N1 and N2 to be set have a relationship of N1 <N2, and are the number of times that no misjudgment is caused even when the flow rate fluctuates in each of a high flow rate and a low flow rate.

  Next, the flow rate measurement value is sampled according to the average number n. That is, the flow rate measurement value Qi is acquired by the ultrasonic measurement unit 2 in step S6, the flow rate measurement value Qi is stored in the data unit 6 (RAM 10c) in step S7, and the sampling number is set to the average number n set in step S8. repeat. When the sampling of the flow rate measurement value is completed, in step S9, the total of the sampled flow rate measurement values Qi is divided by the average number n (arithmetic average) to calculate the average flow rate Qave. Next, in step S10, the cutoff time corresponding to the flow rate region is determined from the average flow rate Qave, and the remaining time of the usage time timer unit 8 is controlled in step S11. In addition, the process of this step S11 performs the process which sets the time to the use time timer part 8, when the interruption | blocking time is determined initially, and when the interruption | blocking time is determined according to flow volume after that, The remaining time is set according to the current flow rate range from the current time and flow rate.

  Thus, when the average flow rate is calculated, the average number is set to a small first predetermined value (N1) when the flow rate is high, and is set to a large second predetermined value (N2) when the flow rate is low. The average flow rate is determined by the number of samplings. Therefore, in the measurement of the instantaneous flow rate, when the flow rate is high, processing is performed with a small number of samplings, so that it is possible to immediately respond to the flow rate fluctuation. In the case of a high flow rate, the influence of the flow rate variation is very small, so a small number of samplings may be used. On the other hand, when the flow rate is low, processing is performed with a sufficient number of samplings, so that the influence of flow rate fluctuations can be reduced.

  In the embodiment, the case where the first predetermined value (N1) and the second predetermined value (N2) are switched has been described, but N1 <N2 <N3 <... The average number is set by switching a plurality of predetermined values such as the first predetermined value (N1), the second predetermined value (N2), the third predetermined value (N3),. Also good.

It is a functional block diagram of an electronic gas meter concerning an embodiment of the invention. FIG. 2 is a block diagram of the main part of the gas meter. It is a functional block diagram of the electronic gas meter which enforces the flow rate presence / absence determination method. It is a principal part block diagram of the gas meter. It is a flowchart of the interruption process of CPU of the gas meter in embodiment of this invention.

Explanation of symbols

1 Control Unit 2 Ultrasonic Measurement Unit 3 Flow Rate Monitoring Unit (Flow Rate Change Detection Means)
4 Average number determination unit (mean number determination means)
5 Average Value Calculation Unit 6 Data Unit 7 Blocking Time Determination Unit 8 Usage Time Timer Unit 9 Blocking Determination Unit 10 Microcomputer 10a CPU
10b ROM
10c RAM
20 Flow rate detection unit 30 Blocking unit 100 Gas meter (gas blocking device)

Claims (1)

The instantaneous flow rate of gas is measured at a predetermined sampling period, and the average flow rate is obtained by averaging the sampling number from a plurality of sampled measurement values, and based on the allowable usage time corresponding to the flow rate range of the average flow rate. A gas shut-off device that shuts off a gas flow path when it is determined that the gas usage state is abnormal,
A means that is realized by an interrupt process that is started at a predetermined timing and executed in parallel with the main process, and a flow rate change detecting means that detects a change in the gas flow rate, and a flow rate change detected by the flow rate change detecting means. An average number determining means for determining the average number of the averaging according to the instantaneous flow rate of the gas, and a use time timer unit for measuring the allowable use time ,
The average number determined by the average number determining means is the number of times that no erroneous determination is made even under flow rate fluctuations in each of a high flow rate and a low flow rate, and a first predetermined value N1 having a relationship of N1 <N2. And a second predetermined value N2 are determined in advance,
Continue monitoring the flow rate change by the flow rate change detecting means,
Wherein if there is the underlying flow rate range corresponding to the flow rate of the allowable use time, and continues to be the absence of flow rate change, when the remaining time of the use time timer becomes zero, to be shut off interrupting determination unit To the control unit
When there is a change in flow rate, the average number determining means determines the average number to the first predetermined value N1 if the instantaneous flow rate is greater than the specified flow rate, and the instantaneous flow rate must be greater than the specified flow rate. determining the field the average number to the second predetermined value N2, and characterized in that calculating the average flow rate of the instantaneous flow rate by the number average is the determined, controls the remaining time of the use time timer unit from the average flow rate Gas shut-off device.

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